This invention relates to an apparatus for changing artificial snow made by an artificial snow making apparatus to wet snow in order to conduct a snow settling test.
One conventional artificial snow making machine is disclosed, for example, in Japanese Patent Laid-Open No. 165,566/1986.
This prior art technique will be described with reference to FIG. 2 of the accompanying drawings. This apparatus comprises a vertical cooling tower 4, a snowfall chamber 1 connected to the bottom of cooling tower 4 and having an opening 3 at the ceiling thereof and which is covered by the cooling tower 4, a first cooler 9 for cooling the air inside the cooling tower 4, and inner cylinder 12 disposed inside the cooling tower 4 in such a manner as to extend in the longitudinal direction of the cooling tower 4 and having an opening at the bottom thereof which is communicated with the opening 3 of the snowfall collection chamber 1, a circulation pipe 13 communicating the top and lower end of the inner cylinder 12, a variable speed blower 14 disposed at an intermediate portion of the circulation pipe 13, a humidifier 15 for supplying moisture into the inner cylinder 12 in the proximity of the lower end of the inner cylinder 12 and a snow seed feeder for supplying ice crystals into the inner cylinder in the proximity of the humidifier 15.
No apparatus is known in the art which changes the snowfall obtained by such an artificial snow making apparatus to wet snow.
A snow-covered power transmission line undergoes torsion in winter and is broken from time to time. This problem occurs particularly when the snow is wet snow.
A snow settling test can be conducted at the time of a natural snowfall in winter but wet snow is not always obtained at the time of natural snowfall. Even in Hokkaido which is the northernmost part of Japan, a wet snowfall may be observed only once a winter or not at all. Therefore, the snow settling test is carried out by sieving the outdoor snow to granular snow, blowing a mist of 0.degree. C. onto the snow to wet it and causing the snow to impinge against the sample (cable) inside an air channel for snow settlement.
The problem here is that the properties of the snow in the snow settling test are entirely different from those of the natural wet snow, though the test uses the natural snow, and a reliable correlation cannot be established between them so that the snow settling test cannot be carried out accurately.
Accordingly, there is a strong demand for an apparatus for changing the artificial snow to wet snow which can provide wet snow having properties almost equivalent to those of the natural wet snow and which can immediately supply the wet snow thus obtained to the snow settling test.
The snow made by the above-described conventional artificial snow making apparatus has the same crystal form as that of the natural snow, but since the former is produced at a low temperature in the range of from about -5.degree. C. to -15.degree. C., its water content is low.
When formed high up in the sky, natural snow becomes wet snow if the temperature on the ground is about 0.degree. C. Therefore, it is possible to change the artificial snow formed in the artificial snow making apparatus and falling thereinside to wet snow by raising the temperature.
If the temperature of the snowfall chamber (test chamber) disposed at a lower part of the artificial snow making apparatus is raised in order to obtain the wet snow, however, the air in the snowfall chamber rises due to convection and the air having a negative temperature inside the inner cylinder 12 drops so that the ice crystals that have not yet grown to snowfall and the snow cannot turn to the wet snow.
For this reason, too, there is a strong demand for the development of an apparatus for changing the snow obtained from the artificial snow making apparatus to wet snow in order to carry out the snow settling test.